Medical devices and insertion systems and methods

ABSTRACT

Implantable medical devices, systems, methods and kits for transcutaneous insertion of the implantable medical devices are provided.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/171,388, filed Jun. 28, 2011, which claims the benefit ofU.S. Provisional Application No. 61/359,815, filed Jun. 29, 2010,entitled “Medical Devices and Insertion Systems and Methods”, both ofwhich are incorporated herein by reference in their entireties for allpurposes.

BACKGROUND

The introduction and temporary implantation through the skin, e.g.,transcutaneously, percutaneously and/or subcutaneously, of medicaldevices has become very common in the treatment and/or diagnosis ofpatients inflicted with or suffering from any one of many differenttypes of conditions. These implantable medical devices include those forthe infusion of therapeutic or diagnostic agents, such as an infusioncannula, as well as those for monitoring a given parameter, such as asensor, that indicates a certain bodily condition, e.g., a patient'sglucose level, or the actual state of a treatment, e.g., monitoring theconcentration of a drug dispensed to the patient or a body substanceinfluenced by the drug.

In recent years, a variety of temporarily implantable sensors have beendeveloped for a range of medical applications for detecting and/orquantifying specific agent(s), e.g., analytes, in a patient's body fluidsuch as blood or interstitial fluid. Such analyte sensors may be fullyor partially implanted below the epidermis in a blood vessel or in thesubcutaneous tissue of a patient for direct contact with blood or otherextra-cellular fluid, such as interstitial fluid, wherein such sensorscan be used to obtain periodic and/or continuous analyte readings over aperiod of time. Certain transcutaneous analyte sensors have anelectrochemical configuration in which the implantable portion of thesesensors includes exposed electrodes and chemistry that react with atarget analyte. At an externally located proximal end of the sensor areexposed conductive contacts for electrical connection with a sensorcontrol unit which is typically mountable on the skin of the patient.One common application of such analyte sensors systems is in themonitoring of glucose levels in diabetic patients. Such readings can beespecially useful in monitoring and/or adjusting a treatment regimenwhich may include the regular and/or emergent administration of insulinto the patient. Examples of such sensors and associated analytemonitoring systems can be found in U.S. Pat. Nos. 6,134,461; 6,175,752;6,284,478; 6,560,471; 6,579,690; 6,746,582; 6,932,892; 7,299,082;7,381,184; 7,618,369 and 7,697,967; and U.S. Patent Publication Nos.2008/0161666, 2009/0054748, now U.S. Pat. No. 7,885,698, 2009/0247857,now U.S. Pat. No. 8,346,335, and 2010/0081909, now U.S. Pat. No.8,219,173, the disclosures of each of which are incorporated byreference herein.

These sensor devices may be designed to be positioned manually, e.g., bya user or a healthcare worker, with or without the use of an insertiondevice, and/or automatically or semi-automatically with the aid of asensor insertion device. Some of these insertion devices include anintroducer needle or cannula having a slotted or hollow configuration inwhich a distal portion of the sensor is slidably carried to the desiredimplantation site, e.g., subcutaneous site, after which the insertionneedle can be slidably withdrawn from the implanted sensor. Examples ofsuch insertion devices are disclosed in U.S. Pat. No. 7,381,184.

The subcutaneous or other placement of such sensors, or any medicaldevice, produces both short-term and longer-term biochemical andcellular responses which may lead to the development of a foreign bodycapsule around the implant and, consequently, may reduce the flux ofanalyte to the sensor, i.e., may reduce the sensitivity or accuracy ofthe sensor function. Although many of these sensor systems are intendedto be implanted over a relatively short period of time, e.g., 3-10 days,the biochemical and cellular responses begin immediately upon insertionand may have a profound and varying effect on glucose transport, oftenrequiring numerous calibrations over the course of the sensor'simplantation period. Besides the technical aspects of recalibration andthe burden upon the patient to recalibrate an implantable sensor,placing the burden of calibration in the hands of patients presentssafety and accuracy issues.

The extent of the immune response presented by implantable sensors, andthe resulting sensor calibration and performance issues, are exacerbatedby the size of the implantable portion of the sensor, often referred toas the sensor tail, and/or by the sensor introducer. A relatively largesensor tail and/or introducer outer diameter results in a more traumaticintroduction which, in turn, produces a greater immune response to thesensor, as well as increased pain and discomfort felt by the patient.Accordingly, an objective of sensor manufacturers has been to minimizesensor and introducer size while providing a highly reliable andreproducible product. Such sensor miniaturization, however, requiresextremely precise fabrication processes and equipment which increasemanufacturing costs. For example, modifying an introducer needle orsharp, e.g., creating the longitudinal slot or slit within it, to allowit to accept a sensor requires use of very expensive laser equipment.Reducing introducer size necessarily requires reducing sensor sizewhich, without precision fabrication and the use of highly expensivematerials, will sacrifice sensor quality and reliability. Because thesurface area of the electrodes or conductive traces on theseminiaturized sensors is so limited, the conductive material itself mustbe super conductive and highly reliable, which is why many currentlyavailable implantable sensors are made with gold or platinum conductivetraces, further adding to the cost of these sensors and their associatedmonitoring systems.

Accordingly, it would be highly desirable to provide a sensor design andassociated sensor introducer, and their combined assembly, which aresized and configured to minimize trauma, pain and the immune response tosensor insertion/implantation without sacrificing sensor performance,accuracy and reliability, and which are also relatively inexpensive tomanufacture.

SUMMARY

Embodiments of implantable medical devices and methods and devices forpositioning at least a portion of the medical devices beneath theepidermal layer of skin, e.g., transcutaneously, are described. Aportion or the entirety of the medical devices may be implanted in ablood vessel, subcutaneous tissue, or other suitable body location.Embodiments of the implantable medical devices may provide therapeuticand/or diagnostic functions, such as the delivery of an agent to withinthe body or the withdrawal of a bodily fluid, or may be used for thecontinuous and/or automatic in vivo monitoring of the level of a bodilyparameter. In certain embodiments, the implantable medical device is anin vivo analyte sensor for the continuous and/or automatic detection andmeasurement of one or more selected analytes.

The subject implantable medical devices as well as the devices forinserting them transcutaneously have very low profiles and dimensions toreduce the pain experienced by the patient and to reduce the traumaticeffect on the tissue, thereby reducing the immune response to theinsertion process and subsequent subcutaneous residence of the medicaldevice. Furthermore, the implantable medical devices and their insertiondevices are each complimentarily configured to be removably coupledtogether in a manner that enables a reduced profile while maximizing thefunctional surface area of the implantable device, and therebyoptimizing device performance, accuracy and reliability.

Embodiments of the present disclosure include implantable sensors andsensor introducers having complimentary configurations and an operativeassembly which provide a minimal combined cross-sectional dimension. Inparticular, the introducer is configured to carry a sensor about itsouter surface rather than inside a slit or slot within its corestructure. This configuration reduces the necessary introducer size.Moreover, a unique manner of coupling the sensor to the introducer doesnot sacrifice the functional surface area of the sensor, and in certainembodiments allows for an increased functional surface area, therebyoptimizing sensor performance, accuracy and reliability. In certainembodiments, the increased functional surface area of the sensor enablesthe number of sensing elements provided on a sensor to be maximized.

Embodiments of the subject medical devices have implantable portionswhich have tubular constructs having cross-sectional shapes anddimensions to provide a frictionally slidable arrangement with acylindrical introducer, such as a needle or sharp, when operativelypositioned within the lumen of the tubular structure. Thecross-sectional shape of the tubular structures of the implantabledevices (and the corresponding cross-sectional shape of the introducersused to implant them) may have any shape including, but not limited to,circular, oval, non-circular, square, rectangular, etc., but mayoptimally have a configuration which minimizes cross-sectional surfacearea, thereby minimizing tissue trauma and pain, while maximizing theexternal or outer surface area of the implant, thereby optimizingfunctionality and performance of the device.

In certain embodiments of the subject medical devices, thenon-implantable portion(s) of the device may have a non-tubularconfiguration, such as a substantially planar configuration, but mayhave any suitable construct for coupling with another component, such asa skin-mounted control unit. The non-implantable portion of the subjectdevices may comprise more than one section or sub-portion, e.g., aportion positioned proximally of the implantable distal portion and anintermediate portion extending between the non-implantable proximalportion and the implantable distal portion which may have a construct,e.g., that is flexible, bendable, conformable, etc., which facilitatesthe relative positioning of the non-implantable proximal portion withthe implantable distal portion of the device.

The tubular construct of the implantable portions of the subject devicesmay be formed by any suitable means given the overall construct of thedevice. In certain embodiments, based on the necessary non-tubularconstruct of the non-implantable portion of devices and/or thelimitations of fabricating the devices in a tubular form or only aportion of the device in a tubular form, the subject devices, includingthe implantable portions, have an initial, non-operative planarconstructs. For example, certain of the subject devices are in vivoelectrochemical sensors for measuring or monitoring a physiological orbiological aspect of the body, such as analytes or the like, whereby theelectrochemical elements of the sensors, i.e., the electrodes andchemical sensing components, are most easily, efficiently and/oreconomically fabricated on substrate material provided in an initialplanar form. As such, the final, operative tubular construct of theimplantable portion of the sensor is required to be formed from theinitial, non-operative planar construct. This may be accomplished byvarious processes of the present disclosure which include folding,wrapping or winding a portion of the flat or planar construct into thedesired tubular shape.

Alternatively, the entirety of the device may be provided in a tubularform and then modified in part to provide a planar portion. Still yet,the tubular and planar portions may be fabricated from separatestructures, whereby the active planar structure, e.g., having theelectrical/chemical components, thereon, is coupled to an inactivetubular structure, e.g., a tubular sheath, which provides only amechanical means for being carried by an introducer for transcutaneousinsertion.

These and other objects, advantages, and features of the presentdisclosure will become apparent to those persons skilled in the art uponreading the details of the present disclosure as more fully describedbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read in conjunction with the accompanying drawings. Itis emphasized that, according to common practice, the various featuresof the drawings are not to-scale. On the contrary, the dimensions of thevarious features are arbitrarily expanded or reduced for clarity.Included in the drawings are the following figures:

FIGS. 1A and 1B illustrate planar and perspective views, respectively,of an embodiment of an implantable medical device of the type which isimplantable with the insertion devices and methods of the presentdisclosure;

FIG. 2 is a perspective view of an embodiment of an insertion device ofthe present disclosure;

FIG. 3A is an isometric view of the medical device of FIGS. 1A and 1Boperatively coupled to the insertion device of FIG. 2, collectivelypositioned on an insertion needle for transcutaneous implantation; FIG.3B is a cross-sectional view taken along lines B-B of FIG. 3A;

FIG. 4 is a plan view of a first side of another embodiment of animplantable medical device/sensor of the present disclosure;

FIGS. 5A and 5B are perspective and end views, respectively, of themedical device/sensor embodiment of FIG. 4 in a bent or angledconfiguration for operative engagement with an introducer or insertiondevice for transcutaneous insertion;

FIGS. 6A-6C are perspective, top and side views, respectively, of themedical device/sensor of FIGS. 4, 5A and 5B operatively engaged with atranscutaneous introducer of the present disclosure;

FIGS. 7A and 7B are plan and side views, respectively, of anotherembodiment of an implantable medical device/sensor of the presentdisclosure;

FIGS. 8A-8C are perspective, top and end views, respectively, of themedical device/sensor embodiment of FIGS. 7A and 7B in a bent or angledconfiguration for operative engagement with an introducer or insertiondevice for transcutaneous insertion;

FIGS. 9A-9C are perspective, top, and end views, respectively, of themedical device/sensor of FIGS. 7A, 7B and 8A-8C operatively engaged witha transcutaneous introducer of the present disclosure;

FIG. 10 is a perspective view of another embodiment of an implantablemedical device of the present disclosure;

FIG. 11A is an isometric view of the medical device of FIG. 10operatively positioned on an insertion needle for transcutaneousimplantation; FIG. 11B is a cross-sectional view taken along lines B-Bof FIG. 11A; and

FIGS. 12A-12F provide perspective and end views of an embodiment of animplantable medical device of the present disclosure in various stagesof fabrication.

DETAILED DESCRIPTION

Before the subject devices, systems and methods are described, it is tobe understood that this disclosure is not limited to particularembodiments described, as such may, of course, vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting, since the scope of the present disclosure will be limited onlyby the appended claims.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimits of that range is also specifically disclosed. Each smaller rangebetween any stated value or intervening value in a stated range and anyother stated or intervening value in that stated range is encompassedwithin the present disclosure. The upper and lower limits of thesesmaller ranges may independently be included or excluded in the range,and each range where either, neither or both limits are included in thesmaller ranges is also encompassed within the disclosure, subject to anyspecifically excluded limit in the stated range. Where the stated rangeincludes one or both of the limits, ranges excluding either or both ofthose included limits are also included in the disclosure.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which the present disclosure belongs. As used herein, theterms transcutaneous, subcutaneous and percutaneous and forms thereofmay be used interchangeably.

All publications mentioned herein are incorporated herein by referenceto disclose and describe the methods and/or materials in connection withwhich the publications are cited. It is understood that the presentdisclosure supersedes any disclosure of an incorporated publication tothe extent there is a contradiction. The publications discussed hereinare provided solely for their disclosure prior to the filing date of thepresent application. Nothing herein is to be construed as an admissionthat the present disclosure is not entitled to antedate such publicationby virtue of prior invention. Further, the dates of publication providedmay be different from the actual publication dates which may need to beindependently confirmed.

It must be noted that as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include plural referents unless thecontext clearly dictates otherwise.

As will be apparent to those of skill in the art upon reading thisdisclosure, each of the individual embodiments described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentdisclosure.

Generally, the present disclosure relates to implantable medicaldevices, methods for fabricating the implantable medical devices, andsystems and methods for positioning or inserting an implantable medicaldevice at least partially beneath the epidermal layer of skin. Thesubject devices may be implantable to provide a therapeutic and/ordiagnostic function and also configured to facilitate their owntranscutaneous implantation.

In certain embodiments, the implantable medical devices are sensors fordetecting and measuring agents within bodily fluid, with particularembodiments that include analyte sensors for the continuous and/orautomatic in vivo detection and monitoring of the level of an analyte.Analytes that may be monitored by the subject sensors include, but arenot limited to, acetyl choline, amylase, bilirubin, cholesterol,chorionic gonadotropin, creatine kinase (e.g., CK-MB), creatine,creatinine, DNA, fructosamine, glucose, glutamine, growth hormones,hormones, ketone bodies, lactate, oxygen, peroxide, prostate-specificantigen, prothrombin, RNA, thyroid stimulating hormone, and troponin.Other of the subject sensors may be configured to detect and measure theconcentration of drugs or other therapeutic agents, such as, forexample, antibiotics (e.g., gentamicin, vancomycin, and the like),digitoxin, digoxin, drugs of abuse, theophylline and warfarin.

Embodiments of the subject disclosure are now further described withreference to the accompanying figures and with respect to implantable,partially implantable or in vivo sensors or sensing devices, where suchdescriptions are in no way intended to limit the scope of the presentdisclosure. It is understood, however, that the embodiments of thepresent disclosure are applicable to any medical device in which atleast a portion of the device is intended to be positioned beneath theepidermis. Furthermore, while the implantable medical devices describedin this detailed description have planar and/or tubular configurations,such shapes and descriptions thereof are not intended to be limiting, asthe medical devices may have any suitable shape, including non-planarand non-tubular configurations, or may have a wire configuration.

Referring now to the figures and to FIGS. 1A and 1B in particular, thereis illustrated an analyte sensor 10 which in certain embodiments isconfigured for implantation through the surface of the skin of apatient. Sensor 10 may be described as having a proximal portion 12, anintermediate or bridging section or portion 14 and a distal portion 16.At least the implantable portion of the substrate, i.e., distal portion16 or a sub-portion thereof, may be flexible (although rigid sensors mayalso be used for implantable sensors) to reduce pain to the patient anddamage to the tissue caused by the insertion and/or extendedimplantation, i.e., “wearing”, of the sensor. A flexible substrate oftenincreases the patient's comfort and allows for a wider range ofactivities. Suitable materials for a flexible substrate include, forexample, non-conducting plastic or polymeric materials and othernon-conducting, flexible, deformable materials. Examples of usefulplastic or polymeric materials include thermoplastics such aspolycarbonates, polyesters (e.g., Mylar and polyethylene terephthalate(PET)), polyvinyl chloride (PVC), polyurethanes, polyethers, polyamides,polyimides, or copolymers of these thermoplastics, such as PETG(glycol-modified polyethylene terephthalate).

Referring again to FIGS. 1A and 1B, provided on distal portion 16 ofsensor 10 is a sensing element 18 including a sensing material and atleast one working electrode configured to detect one or more selectedanalytes. Sensing element 18 may be based on “enzyme electrode”technology in which an enzyme, such as glucose oxidase or glucosedehydrogenase where the selected analyte is glucose, to provide anelectrochemical enzymatic reaction when in contact with biologicalfluid. A detailed description of such enzymatic electrode technology isprovided in for example, U.S. Pat. Nos. 6,134,461; 6,175,752; and6,284,478, which are herein incorporated by reference.

Sensor 10 may also include one or more optional components, such as, forexample, one or more additional working electrodes, a referenceelectrode, a counter electrode and/or a counter/reference electrode, anda temperature probe. The one or more sensor electrodes extend fromsensing element 18 to the proximal portion 12 of sensor 10, over oneside, i.e., an active side, of the sensor 10, including surfaces 12 a,14 a and 16 a, where they terminate in respective electrical contactsfor coupling to corresponding electrical contacts of a sensorcontrol/data processing unit (not shown) of an analyte monitoringsystem. While only a single sensing element 18 is illustrated at a verydistal end of distal portion 16, any suitable number of sensing elementsmay be provided at any location along the length of the implantableportion of distal portion 16.

The subject sensors may be provided as part of an analyte monitoringsystem which includes a sensor control/data processing unit (not shown)having a housing adapted for placement on the skin surface and forcoupling with the sensor electrode(s) on the proximal portion 12 ofsensor 10. Communication electronics may also be disposed within thehousing for relaying or providing data obtained using the sensor toanother device such as a remotely located device, e.g., RF transmitteror RFID electronics. The control/data processing unit may also include avariety of optional components, such as, for example, adhesive foradhering to the skin, a mounting unit (which may include adhesive), areceiver, a processing circuit, a power supply (e.g., a battery), analarm system, a data storage unit, a watchdog circuit, and a measurementcircuit. The analyte monitoring system may also include a display unitprovided on the on-skin control/data processing unit or on a separateunit remote from the on-skin unit which includes a receiver forreceiving data transmitted from the on-skin unit. The remote unit mayoptionally include a variety of components, such as, for example, a userinput mechanism, e.g., keypad, etc., a receiver, transceiver ortransmitter, an analyzer, a data storage unit, a watchdog circuit, aninput device, a power supply, a clock, a lamp, a pager, a telephoneinterface, a computer interface, an alarm or alarm system, and acalibration unit. Additionally, the analyte monitoring system or acomponent thereof may optionally include a processor capable ofdetermining a drug or treatment protocol and/or a drug delivery system.Examples of such analyte monitoring systems are provided in U.S. Pat.Nos. 6,175,752; 6,284,478; 6,134,461; 6,560,471; 6,746,582; 6,579,690;6,932,892; and 7,299,082; incorporated by reference herein.

Referring again to FIGS. 1A and 1B, the intermediate or bridging section14 of sensor 10 may be flexible or bendable (as it would be with sensorembodiments made of the materials listed above) to allow for selectivelypositioning the proximal portion 12 relative to distal portion 16 toallow for a lower profile configuration above the skin surface.Alternatively, proximal portion 12 may otherwise be formed or providedat a fixed angle relative to distal portion 16, for example, if sensor10 is made of more rigid materials such as ceramic, or the like, orconnected or coupled to another component such as, for example,electronics components (printed circuit board, etc.). In either case,the proximal portion 12 may be positioned or may be positionable at anangle relative to distal portion 16 in the range from about 30° to about180°, and more typically in the range from about 80° to about 150°. Thesubject sensors may be configured to be folded or bent in any suitabledirection to accommodate the corresponding construct of the systemcomponents with which the proximal portion is to be coupled. Forexample, in the embodiment of FIG. 1B, intermediate portion 14 is flexedto provide proximal portion 12 at approximately a 90° angle to distalportion 16 such that the proximal surface 12 a and distal surface 16 aof a first, front or active side of sensor 10, i.e., the side of thesensor on which the sensing components are provided, are substantiallyinwardly facing. Alternatively, intermediate portion 14 may be flexed inthe opposite direction such that proximal surface 12 b and distalsurface 16 b of a second, back or inactive side of sensor 10 aresubstantially inwardly facing, where “inactive” means that no sensingcomponents are provided thereon. In either case, the correspondingelectrical contacts of the analyte monitoring control unit with whichthe proximal portion 12 is to be coupled must be positioned andconfigured to operatively couple with the sensor contacts on activeproximal surface 12 a, which may require proximal side 12 a to facedownward or toward the skin surface, as in FIG. 1B, or upward or awayfrom the skin surface, as the case may be.

Sensor 10 may be further designed such that the central or medianlongitudinal axis of distal portion 16 may be disposed in a differentplane in comparison to the central or median longitudinal axis of theintermediate portion and/or proximal portion 12. That is, certainembodiments of the sensor 10 may include the central longitudinal axisof distal portion 16 aligned substantially in parallel with the centrallongitudinal axis of the intermediate portion 14 and/or proximal portion12 in a first geometric plane. In this manner, certain embodiments ofthe sensor 10 may be configured to more optimally accommodate the axisof an insertion device (not shown), discussed in greater detail belowwith respect to FIG. 3A. In the illustrated embodiment of FIGS. 1A and1B, this is accomplished by a jog or shoulder 15 in the sensor substratematerial between or about the juncture of the intermediate portion 14and distal portion 16. Additionally, to facilitate alignment and/oroperative coupling of distal portion 16 with an insertion device, alongitudinal cut or opening 17 may be provided within intermediateportion 14 (see FIG. 1A) to provide for a proximal tip portion 20extending axially from distal portion 16 when sensor 10 is in a flexed,bent, curved, stressed, articulated or angled state or condition, asshown in FIG. 1B. The design or shape of the juncture betweenintermediate portion 14 and distal portion 16 described above in certainembodiments allows for such ambidextrous angling of the sensor.

Sensor 10, as well as the planar portions of other sensors disclosedherein, may be fabricated from well-known processes, either individuallyor in batches using web-based manufacturing techniques which aredisclosed in U.S. Pat. No. 6,103,033, the disclosure of which isincorporated by reference in its entirety. With the latter, a continuousfilm or web of substrate material is provided and heat treated asnecessary. The web may have precuts or perforations defining theindividual sensor precursors. The various sensing elements andcorresponding electrodes are then formed on the substrate web by one ormore of a variety of techniques including, for example, by means of anink jet printing process, a high precision pump and/or footed needle.Additional description of using a high precision pump with a footedneedle can be found in U.S. patent application Ser. No. 12/752,109, thedisclosure of which is incorporated herein by reference for allpurposes. The respective material layers may be provided over a webbingof sequentially aligned sensor precursors prior to singulation of thesensors or over a plurality of sensors/electrodes where the sensors havebeen singulated from each other prior to provision of the one or morematerial layers. Next, any suitable subtractive process may be employedto remove portions of the material layers to obtain the desired size andconstruct of the sensing elements and electrodes. One such processincludes using a laser to ablate away or trim the targeted material.After forming the individual sensing elements and electrodes, the sensorprecursors, i.e., the template of substrate material (and the conductiveand sensing materials), may be singulated from each other using anyconvenient cutting or separation protocol, including slitting, shearing,punching, laser singulation, etc. The just-described fabricationtechniques are especially suitable for implantable sensors and othermedical devices having completely flat or planar constructs, such as thesensor 10 of FIGS. 1A and 1B.

Referring now to FIG. 2, there is shown one embodiment of a medicaldevice introducer or insertion mechanism in a sheath configuration 22 ofthe present disclosure for inserting a medical device, such as analytesensor 10, transcutaneously into a patient. Sheath 22 is configured tobe collectively implanted, or at least partially implanted, with themedical device for which it facilitates implantation and, subsequently,remain with and be simultaneously removed with the device, e.g., afterthe sensor's useful sensing life. As such, it may be made of the samematerial as the medical device to be implanted and have the sameflexibility/rigidity/articulation as that of the device in certainembodiments. For example, sheath 22 may be fabricated from the samesubstrate material as sensor 10, e.g., being formed by thin film tubingtechniques. Alternatively, sheath 22 may be made of a material having agreater rigidity than the medical device it is designed to implant inorder to facilitate insertion into and removal from the skin.

In certain embodiments, inserter or introducer sheath 22 has anelongated configuration having an exterior surface 24 configured forfixedly engaging a surface of the medical device to be inserted andhaving an interior lumen 26 having a shape and dimension to accommodatean introducer, such as introducer needle or insertion needle 30illustrated in FIG. 3A. Inserter 22 may have any suitable exterior andinterior configuration and dimensions to accommodate the medical deviceand introducer, respectively. For example, inserter 22 may have atubular configuration having an exterior surface 24 having a length andcircumferential diameter sufficient to engage with, support and carrythe distal portion 16 of sensor 10, as illustrated in FIG. 3A, but mayhave any exterior surface configuration to accommodate the medicaldevice to be implanted. For example, inserter sheath 22 may have anexterior surface 24 that has a cylindrical configuration, asillustrated. With sensor portion 16 being relatively flexible, it can bedeformed to fit about the rounded exterior surface of sheath 22. Inembodiments where sensor portion 16 is less flexible, portion 16 may beformed with a cross-sectional shape substantially matching the exteriorcross-section of sheath 22. For example, sensor portion 16 may have anarcuate cross-section having a radius of curvature which matches,complements, or correlates with that of the arcuate exterior of sheath22. Alternatively, sheath 22 may have a flat exterior surface forcarrying the medical device where the remainder of the exterior surfaceis annular or cylindrical to facilitate atraumatic insertion into theskin. The latter embodiment may be useful where sensor 10, or at leastdistal portion 16, has a flat or planar design and is made of a morerigid material and not easily flexed or folded. Alternatively, theexterior cross-section of inserter sheath 22 may have a square orrectangular configuration, or any other suitable configuration. Theinterior cross-sectional shape 26 of inserter 22 is typically annular toaccommodate a cylindrical needle, such as introducer needle 30 of FIGS.3A and 3B, but may have any shape to accommodate that of the introducer,including, but not limited to, oval, non-circular, square, rectangular,etc. Needle 30 may be in the form of a hypodermic needle, mandrel, sharpor the like. When provided collectively, sheath 22 and needle 30 form anintroducer or insertion kit, where the sheath is a single-useimplantable component of the kit and the needle may be removable afterimplantation of the medical device.

An operative engagement of the insertion components with sensor 10 isillustrated in FIGS. 3A and 3B with needle 30 slidably engaged withinthe lumen of sheath 22 and the inactive or back side 16 b of distalsensor portion 16 permanently affixed to exterior surface 24 of sheath22, either by mechanical means or by medical grade adhesive. Suitableadhesives include ultraviolet curable adhesives such as cyanocrylateglue.

In order to minimize the physical trauma to the patient and minimize thetissue response to the insertion of the implantable medical device, thecross-wise and length dimensions of sheath 22 should be as small aspossible but sufficient to carry the attached medical device. Withrespect to a transcutaneously analyte sensor 10, for example, sheath 22may have an outer diameter in the range from about 100 μm to about 400μm, and more typically in the range from about 200 μm to about 300 μm,and a length in the range from about 3 mm to about 15 mm. With certainembodiments, the outer diameter, width or semi-circumferential dimensionof the sheath will be substantially the same as that of the medicaldevice to be delivered. This may be the case for embodiments in whichthe portion of the medical device being attached to the sheath issufficiently flexible and, thus, able to easily conform to the outer orcircumferential shape of the sheath. However, if the attachable portionof the medical device is less flexible and unable to readily conform tothe sheath geometry, then the sheath may have to have a largercross-sectional or width dimension than that of the medical device. Asfor the length dimension, in order to provide sufficient stability forinsertion, in certain embodiments sheath 22 may have a length at leastas long as the portion of distal portion 16 which will be positionedbeneath the skin surface, e.g., from about 4 mm to about 8 mm, but maybe longer or shorter than the implantable portion of the device. Thewall thickness of sheath 22 is typically in the range from about 5 μm toabout 40 μm and, in certain embodiments, ranges from about 10 μm toabout 30 μm, but may be thinner or thicker as appropriate. The interiordimension of lumen 26 is such to accommodate the crosswise dimension ordiameter of needle 30 which, for sensors of the type discussed here,typically has a gauge from about 30 gauge to about 33 gauge, but may besmaller or larger depending on the type of medical device and theintended application. As the sensor/sheath assembly is carried on anouter surface of introducer 30, rather than within an interior space,e.g., in a longitudinal slit or lumen of the introducer, thecross-sectional dimension of the introducer 30 is minimized to achievethe objectives of minimal tissue trauma, reduced pain and optimal sensorperformance.

The component assembly, as illustrated in FIGS. 3A and 3B, may beprovided preassembled, i.e., with sensor 10 pre-attached to sheath 22and needle 30 pre-inserted or pre-loaded within sheath 22, from thefactory and packaged accordingly. The pre-assembled component assemblymay further include an on-skin control unit or components thereof.Alternatively, needle 30 may be provided separately and positionedwithin the implantable components, sensor 10 and sheath 22, by the userprior to device implantation. With user-assembled embodiments thatinclude a mechanical means (other than adhesive) for coupling the sensor10 to sheath 22, the sensor may be provided uncoupled from sheath 22.

Referring now to FIG. 4, there is illustrated another embodiment of animplantable analyte sensor 40 of the present disclosure which in certainembodiments is configured for implantation through the surface of theskin of a patient. Sensor 40 has a similar structure to that of sensor10 of FIGS. 1A and 1B, having a proximal portion 42, an intermediate orbridging section or portion 44, and a distal portion 46 having one ormore sensing elements 48; however, for reasons which are discussedbelow, the width dimension 52 b of distal portion 46 (see FIG. 5B) issubstantially greater than that of distal portion 16 of sensor 10. Oneor more sensor electrodes (not shown) extend from sensing element 48 tothe proximal portion 42 of sensor 40, over one side of the sensor,including surfaces 42 a, 44 a and 46 a, where they terminate inrespective electrical contacts for coupling to corresponding electricalcontacts of a sensor control unit (not shown) of an analyte monitoringsystem. Further, like sensor 10, the intermediate or bridging section 44of sensor 40 may be flexible or bendable (as it would be with sensorembodiments made of the materials listed above) to allow for selectivelypositioning the proximal portion 42 relative to distal portion 46, asshown in FIGS. 5A and 5B, at a desired angle, as described above withrespect to sensor 10, to allow for a lower profile configuration abovethe skin surface. Alternatively, proximal portion 42 may otherwise beformed or provided at a fixed angle relative to distal portion 46. Inthe illustrated embodiment, intermediate portion 44 has been flexed,bent or angled in a direction wherein the active sides 42 a and 46 a ofproximal and distal portions 42 and 46, i.e., the sides of the sensor onwhich the sensing components are provided, are outwardly facing.However, intermediate portion 44 may be folded, bent or angled in theopposite direction wherein the respective active sides 42 a, 46 a arefacing inwardly towards each other. Also, like sensor 10, sensor 40 mayhave a jog or shoulder 45 and/or a cut or slit 47 in the sensorsubstrate material to facilitate alignment and coupling of distalportion 46 to an insertion or introducer device.

As discussed previously, the implantable medical devices of the presentdisclosure and their insertion devices are complimentarily configured tobe coupled together in a manner that enables a reduced profile whilemaximizing the functional surface area of the implantable device. Tothis end, as illustrated in FIGS. 6A-6C, distal portion 46 of sensor 40has been rolled or folded about its longitudinal axis in a tubular shapeto provide it in a fully fabricated, operative state by which it can beoperatively coupled to an introducer device 60, which is in the form ofa needle or sharp. More particularly, the longitudinal edges 52 (seeFIG. 5B) of distal portion 46 have been manipulated to be apposed, forexample, in an edge-to-edge or overlapping arrangement, wherein theapposed edges may or may not form a longitudinal seam in the tubularportion. The active surface 46 a of distal portion 46 is provided as theexterior surface when in the tubular state such that the one or moresensing elements 48 are facing outward for exposure to the subcutaneousenvironment and the inactive surface 46 b forms the interior surface ofthe tubular structure having an interior diameter or crosswisedimensions for accommodating introducer 60 in a frictionally slidableengagement. Such a configuration eliminates the need for a separateinsertion sheath 22. The tubular form of distal portion 46 may beprovided, such as by fabrication processes described below, prior tooperative engagement with introducer 60. Alternatively, in otherembodiments, distal portion 46 may be wrapped about introducer 60 andfixed in the tubular format thereafter, either by a coupling mechanism(not shown), by curing or setting treatments, or by virtue of being madefrom a plastically deformable material.

FIGS. 7A and 7B illustrate another embodiment of an implantable sensor70 of the present disclosure in a pre-implant state in which allportions of the sensor are positioned or presented in the same plane.Sensor 70 has a proximal portion 72 which is substantially the same instructure and function to the previously described sensor embodiments.However, while distal portion 74 has a similar function to that ofdistal portions 16 and 46, respectively, of sensors 10 and 40, it isprovided at an angle a from a major or longitudinal axis 75 of proximalportion 72, as best illustrated in FIG. 7A, where angle a is in therange from about 5° to about 30°, and more typically from about 15° toabout 20°, but may be greater or smaller. As will be better understoodbelow, this angled juxtaposition between the proximal and distalportions 72, 74 makes it unnecessary to provide an off-settingintermediate portion as described above with respect to sensorembodiments 10 and 40. While the material characteristics, e.g.,flexibility/rigidity/articulation, and the overall surface area ofdistal portion 74 may be similar to those of distal portions 46 ofsensor 40, the length and width dimensions of distal portion 74, when inthe non-operative, planar configuration of FIGS. 7A and 7B, aretypically longer and narrower, respectively, the purpose of which isalso better understood with reference to the description below. One ormore sensing elements 78, having similar electrochemical features andstructures to those of the previously described sensor embodiments, areprovided on first, front or active surface 74 a of distal portion 74.One or more electrodes (not shown) extend from sensing element(s) 78 toproximal portion 72 and over proximal and distal active surfaces 72 a,74 a. The second, back or inactive side of sensor 70 provides inactiveproximal and distal surfaces 72 b, 74 b.

FIGS. 8A-8C show sensor 70 provided in a flexed, bent, curved, stressed,articulated or angled state or condition in which proximal portion 72 isprovided at approximately a 90° angle to distal portion 74 such thatactive proximal surface 72 a and active distal surface 74 a areoutwardly facing. Alternatively, sensor 70 may be flexed or bent in theopposite direction such that the opposing inactive proximal and distalsurfaces 72 b, 74 b on the back side of sensor 70 are inwardly facing.As with the other sensor embodiments, proximal and distal portions 72,74 may be flexed, bent, curved, stressed, articulated or angled at anysuitable angle and in either direction to provide a coupling profilewith the corresponding electrical contacts of an analyte monitoringcontrol/data processing unit that is acceptable. As best observed inFIGS. 8B and 8C, the angular juxtaposition between the proximal anddistal portions 72, 74, as explained above, laterally displaces distalportion 74 from the longitudinal axis 75 of proximal portion 72 whensensor 70 is in the flexed, bent, curved, stressed, articulated orangled configuration. This displacement or offset (similar to thatprovided by the jog or shoulder of sensors 10 and 40) enables distalportion 74 to be wrapped or wound in a somewhat transverse manner toprovide a tubular configuration for operative coupling with an insertionor introducer needle 80 as shown in FIGS. 9A-9C, while maintaining therelative perpendicular positioning of proximal portion 72. Moreparticularly, distal portion 74 has been rolled, wrapped or wound in adirection partially transversely about its longitudinal axis, e.g., in ahelical fashion. The helical wrapping of distal portion 74 may beprovided in a manner to provide minimal spacing 85 (see FIG. 9C) betweenits windings so as to minimize the overall implantable length of thesensor and/or to provide an exterior surface that is continuous andflush in order to minimize trauma to the tissue uponinsertion/implantation.

When in an operative or implantable configuration, both sensorembodiments 40 and 70 are in a tubular configuration. Because of thetubular design of distal portions 46 and 74, an insertion sheath 22 isnot necessary for the transcutaneous implantation of these sensors,thereby reducing the number of components and the overall cost of thecollective components. Moreover, such a configuration minimizes thecross-sectional dimension of the implantable portion of the sensors(and, thus, minimizes tissue trauma and reduces pain) while maximizingtheir available functional/outer/active surface area to allow for agreater number and/or size of the sensing elements on a singledevice/sensor. Further, the greater functional surface area of thesensors allows for sensor electrodes that need not be so miniaturizedand, thus, may be made of less expensive conductive materials.

The respective tubular configurations of sensors 40, 70 may be providedby various means. In one process, the sensor is fabricated in apreliminary planar form, as in FIGS. 4 and 7A, respectively, byweb-based manufacturing methods or the like described above with respectto sensor 10 of FIGS. 1A and 1B. With such processes, the sensorsubstrate material is made of either a conformable polymer material or ametal or metal alloy, such as stainless steel foil or Nitinol, which isprovided with an insulating layer on the surface that will function asthe outer surface of the sensor in order to insulate the metal substratefrom the electrodes and associated conductive trances. The distalportion of the sensor is then rolled, folded, wound or wrapped, asappropriate, about a cylindrical-shaped mandrel or scaffold and thenheat-set or cured to provide a final, permanent tubular form.Alternatively, the sensor substrate material, or at least that used tofabricate the respective distal portions, may have physical propertieswhich allow it to be plastically conformable or deformable without anysetting or curing treatment. With either process, it may be preferentialto avoid any overlapping of or spacing between the respectivelongitudinal edges 52 (see FIG. 5B) and edges 82 (see FIG. 8C),respectively, of sensors 40, 70 in order to provide a very flush sensorouter surface to minimize tissue trauma upon transcutaneous insertion ofthe sensor. Further, such edge-to-edge precision will minimize the outercross-sectional dimension of the resulting tubular structure. Withsensors made from either of the aforementioned processes, the sensingelement and/or electrodes may be provided or formed on the substratematerial either before or after provision of the tubular shaping.

In yet other embodiments, the sensor or at least the distal orimplantable portion thereof may be provided in an original contiguoustubular form, i.e., wherein there are no seams (seamless) or spaces inthe final structure, without folding, wrapping, winding or coupling thesides or ends of a precursor planar structure. Such embodiments may befabricated by one or more extrusion methods. For example, the sensorsubstrate material may be made of a polymer material which may be formedin the desired tubular shape by an extrusion process, in which case thesensing components, including the conductive materials, are formed orprovided on the substrate material after extrusion. In still otherembodiments, the subject sensors may be fabricated by an extrusionprocess in which the conductive materials, e.g., metal material formingthe electrode and traces, and the non-conductive materials, e.g.,dielectric material forming the substrate, are co-extruded. Examples ofsensors fabricated by extrusion methods are disclosed in U.S.Publication No. 2008/0200897 and U.S. patent application Ser. Nos.12/495,618, issued as U.S. Pat. No. 8,298,158; 12/495,696, now issued asU.S. Pat. No. 8,000,763; 12/495,709; 12/495,712, issued as U.S. Pat. No.8,437,827; and 12/495,730; all of which are incorporated herein byreference in their entireties.

Referring now to FIG. 10, there is an embodiment of an implantablesensor 90 of the present disclosure fabricated according to an extrusionprocess. Sensor 90 has proximal and intermediate portions 92, 94 whichare substantially the same in structure and function to those of sensors40 and 70; however, distal portion 96 of sensor 90 is different in thatit has an original configuration that is tubular or luminal rather thanflat or planar. The material characteristics, e.g., flexibility,rigidity, articulation, etc., and the structural dimensions of distalportion 96 may be similar to those of the previously described sensorembodiments. A sensing element 98 is provided on an active outer surfaceof distal portion 96 having similar electrochemical features andstructures described with respect to the sensing elements describedpreviously. With the greater surface area that a tubular distal portionprovides (rather than the strip configuration), more than one or aplurality of sensing elements (not shown) may be provided, where eachsensing element may be designed to detect a particular analyte or otherbiological agent. Each sensing element 98 may have its own designatedelectrode or electrodes which extend from distal portion 96 to proximalportion 92 via intermediate portion 94. Those skilled in the art willappreciate that the construct of intermediate portion 94 may vary fromthat illustrated to provide a sufficient amount of surface area forbridging multiple electrodes or multiple sets of electrodes across it.As shown in FIGS. 11A and 11B, distal portion 96 of sensor 90 isoperatively positioned or mounted on an insertion or introducer needle100 having dimensions which enable slidable engagement with tubularportion 96 of the sensor.

Where the subject implantable medical devices have partial tubularconstructs, i.e., only a single portion of the device is provided withan original tubular construct and the remaining portions havenon-tubular constructs or are otherwise less amenable to fabrication byextrusion processes, such as with sensor 90 of FIG. 10, a hybridfabrication approach may be taken where at least the tubular portions ofthese devices are formed using extrusion techniques. The othernon-tubular components may be made by conventional web-based processes,such as those described above. The various components of the device maybe coupled together prior to or after providing the variouselectrochemical components thereon, which may be formed by thedeposition, printing, coating and/or removal techniques mentioned above.In other embodiments of the subject devices having both tubular andnon-tubular constructs, however, the same extrusion techniques may alsobe used with the intended non-tubular portions of the devices, which aresubsequently further processed to provide the non-tubular constructs. Anexample of such process is described with respect to FIGS. 12A-12F.

FIGS. 12A and 12B provide a perspective and end views, respectively, ofa tubular-shaped structure or precursor 110 to an implantable medicaldevice of the present disclosure which, in a final form, has anon-tubular or planar portion 112 and a tubular or cylindrical portion114. For electrochemical sensor embodiments as described above, thesensor precursor is made of a substrate material(s) and has dimensionsalso described previously. To provide the planar portion 112, cuts 115 aand 115 b are made into precursor 110 using a laser or the like.Specifically, a longitudinal cut 115 a is made extending from end 112 aof precursor 110 to a distance within the tubular wall which defines thedesired length of the side walls 112 b of planar portion 112, as shownin FIG. 12C. As shown in FIG. 12A, a cross-sectional cut 115 b is alsomade, preferably at the proximal or inside end of longitudinal cut 115a, to define an end 114 a of tubular portion 114, which extends to atleast about halfway or 180° through the precursor wall 110, as shown inFIGS. 12C and 12D, the latter figure being an end view of the former.Depending on the desired extent or width of the intended bridgingsection 116 between tubular portion 112 and planar portion 114,cross-sectional cut 115 b may extend less than or more than 180° withinprecursor wall 110, typically to about 270° or greater. As shown inFIGS. 12C and 12D, the cut side walls 112 b of planar portion 112 arethen separated and folded away from each other to, in certainembodiments, a flattened condition, as illustrated in FIGS. 12E and 12F,the latter figure being an end view of the former. Optionally, planarportion 112 may then be shaped as desired and/or angled relative totubular portion 114 by bending or folding intermediate section orbridging portion 116. The electronic components, e.g., electrodes, andelectrochemical components, e.g., sensing element, etc. may be providedand formed on precursor 110 either prior to or subsequent to thecutting, shaping and bending steps just described.

The respective implantable tubular portion of each of the subject sensordevices functions as a sheath having an interior lumen which slidablyand/or frictionally accommodates an introducer needle which is used totranscutaneously implant the sensor. The introducers usable with thesubject sensors may be in the form of a hypodermic needle, mandrel,sharp or the like and be made of any suitable material and have anexterior surface configuration and length and diameter dimensions tosufficiently engage with, support and carry the distal portion of thesensor. As described above, for use with the subcutaneous analytesensors of the present disclosure, the introducer typically has a gaugefrom about 25 to about 35, and often from about 30 to about 33, but maybe greater or small to accommodate the particular medical device withwhich it is used. As for the length dimension, in order to providesufficient stability for insertion, in certain embodiments, theintroducer has a length at least as long as the section of the sensor'stubular portion which is intended to be positioned beneath the skinsurface, but may be longer or shorter than the implantable portion ofthe device.

To provide an optimal ratio of cross-sectional dimension to functionalsurface area for the tubular distal portions of the subject sensor,their respective dimensions are as follows. For subcutaneousapplications, the tubular distal portions, as well as the tubularinsertion sheath such as sheath 22 of FIG. 2, typically have animplantable length dimension 52 a (see FIG. 5B), 82 a (see FIG. 8C) and102 a (see FIG. 11A), respectively, from about 4 mm to about 6 mm with atotal length sufficient to couple with an on-skin unit. The widthdimension of the sensor distal portions having precursor or pre-finalconfigurations which are non-tubular, e.g., planar, given the typicallygauge values of the introducer needles for transcutaneous insertion ofin vivo analyte sensors, wherein the smaller the introducer gauge, theshorter the planar width dimension of the sensor distal portions, are asfollows. The planar width dimension 52 b (see FIG. 5B) of sensor distalportion 46 of sensor 40 is in the range from about 0.75 mm to about 1.75mm, and in certain embodiments are in the range from about 0.9 mm toabout 1.5 mm. For sensor distal portion 74 of sensor 70, the planarwidth dimension 82 b (see FIG. 8C) is in the range from about 0.75 mm toabout 1.25 mm, and in certain embodiments is about 1.0 mm. When therespective distal portions 46, 74 are in the operative tubularconfiguration (accomplished either by folding, rolling, wrapping,winding, etc. as the case may be), their resultingcross-sectional/diameter dimensions are dependent upon the wallthickness of the respective sensor distal portions and the gauge of theintroducer needle. In certain embodiments, the sensor distal portions orinsertion sheaths have a thickness or wall thickness in the range fromabout 100 μm to about 200 μm, and often between about 125 μm to about175 μm. Of course, any of the aforementioned dimensions may be smalleror greater depending on the type of medical device being implanted andits intended application. The interior cross-sectional shape of thedistal portion of the subject implantable devices when in the operativetubular form is typically annular to accommodate a conventionally shapedneedle introducer, but may have any shape including, but not limited to,oval, non-circular, square, rectangular, etc., which may be formed by acorresponding shaped mandrel, scaffold or extrusion port.

The subject sensors and introducers may be provided from the factory andpackaged accordingly in a pre-assembled, operative engagement with theintroducer pre-inserted or pre-loaded within the sensor's distalportion. If the sensor/inserter combination is useable with an automaticinsertion device or gun, the two components may be pre-assembled alongwith the insertion device. Alternatively, the introducer may be providedseparately and operatively positioned within the distal portion of thesensor by the user just prior to device implantation.

With any of the above-described sensor embodiments, implantation of thesensor involves using the sharp tip of the introducer to penetrate theskin surface and drive the assembly to the desired depth beneath theskin surface, where insertion (and/or retraction) of the needle may bemanual, automatic (where the force and speed of insertion arecontrolled) or semi-automatic. For example, the driving action may beprovided manually by the patient or healthcare provider, where theproximal end of the introducer is equipped with a handle for operativemanipulation by the user. Alternatively, an insertion gun (notillustrated) or the like may be provided having a driving mechanism fordriving the introducer, the sheath and the device being carried by thesheath into the patient. The insertion mechanism may also include aretraction mechanism for removing the introducer (e.g., along theinsertion path but in the opposite direction) while leaving the sensorand sheath within the patient. The driving and/or retraction functionsmay be fully automatic, initiated by a push of a button or the like, orsemi-automatic, requiring some further manipulation by the user.Examples of such automatic or semi-automatic insertion devices aredisclosed in U.S. Patent Nos. 6,175,752 and 7,381,184 and others, eachof which is herein incorporated by reference.

With the subcutaneous implantation of the subject analyte sensorembodiments, the sensing element thereof is positioned under the skin soas to be in continuous contact with bodily fluid, such as blood orinterstitial fluid for continuously or semi-continuously monitoringanalyte levels, such as glucose levels. Of course, depending on the typeof medical device, other functions may be performed by the device. Thesensor is left within the skin for its useful sensing life which may beabout 1 day or more, e.g., from about 3 days to about 30 days or more,e.g., about 7 days, about 10 days, about 20 days, etc.

In certain embodiments, an assembly may comprise a sensor configured fortranscutaneous placement within a subject, the sensor comprising atubular portion and a sensing element disposed on an exterior surface ofthe tubular portion, and a sensor introducer disposable within aninterior lumen of the tubular portion of the sensor and configured totranscutaneously introduce the tubular portion through the skin of thesubject.

In certain aspects, the sensor may include a planar portion extendingproximally from the tubular portion, the planar portion configured forplacement outside the skin of the subject for operative engagement withan external device.

In certain aspects, the planar portion may extend at an angle from thetubular portion.

In certain aspects, the angle may range from about 30° to about 180°.

In certain aspects, the sensor may include a flexible intermediateportion extending between the tubular portion and the planar portion.

In certain aspects, the tubular portion may have a proximal tip portionwhich extends beyond the intermediate portion when the intermediateportion is flexed.

Certain aspects may include an insertion device for driving the sensorintroducer through the skin.

In certain aspects, the sensor may be an analyte sensor.

In certain aspects, the analyte sensor may be a glucose sensor.

In certain aspects, the sensor may include at least one electrodeextending from the sensing element along the exterior surface of thetubular portion.

In certain aspects, the tubular portion may be formed by wrapping aplanar sensor substrate into a tubular configuration.

In certain aspects, the wrapping may comprise apposing longitudinaledges of the planar substrate material.

In certain aspects, the wrapping may comprise a helical configuration.

In certain aspects, the tubular portion may be formed by an extrusionprocess.

In certain aspects, the tubular portion and the planar portion may beformed at least in part by an extrusion process.

In certain embodiments of the present disclosure, a system for insertinga medical device transcutaneously within a subject may comprise anintroducer needle, and a sheath configured for slidable engagement aboutthe introducer needle, wherein an exterior surface of the sheath isconfigured for fixed engagement with a medical device, and furtherwherein the sheath is configured to remain fixedly engaged with themedical device after transcutaneous insertion of the medical device.

Certain aspects may include an adhesive material for fixed engagement ofthe medical device with the sheath.

In certain aspects, the sheath may comprise a polymer material.

In certain aspects, the sheath may comprise one of a circular, oval ornon-circular shape.

In certain aspects, the introducer needle may be part of an automatedinsertion device.

In certain aspects, the medical device may have a proximal portion and adistal portion, wherein only the distal portion is configured forengagement with the sheath and for transcutaneous implantation.

In certain aspects, the medical device may comprise an intermediateportion extending between the proximal portion and the distal portion,the intermediate portion being flexible to provide an angularrelationship between the proximal portion and the distal portion.

In certain aspects, the medical device may comprise a sensor.

In certain aspects, the sensor may be an analyte sensor.

In certain aspects, the analyte sensor may be a glucose sensor.

In certain embodiments of the present disclosure, a method ofintroducing a sensor through the skin of a subject may compriseproviding the sensor coupled to an exterior surface of a sheath, andusing an introducer needle disposed within the sheath totranscutaneously position the sensor and the sheath through the skin ofa subject.

Certain aspects may include removing the introducer needle from thesubject, wherein after removal of the introducer needle from thesubject, the sensor and the sheath remain transcutaneously positioned.

In certain aspects, providing the sensor coupled to the sheath maycomprise adhering the sensor to the exterior surface of the sheath.

In certain embodiments of the present disclosure, an analyte sensor maycomprise a tubular portion, at least a portion of which is configuredfor transcutaneous placement within a subject, a planar portionextending proximally from the tubular portion, and at least oneelectrode disposed on an outer surface of the tubular portion and on asurface of the planar portion.

In certain aspects, the planar portion may extend at an angle from thetubular portion.

In certain aspects, the angle may range from about 30° to about 180°.

Certain aspects may include an intermediate portion extending betweenthe proximal portion and the tubular portion, the intermediate portionbeing bendable to provide an angular orientation between the proximalportion and the tubular portion.

In certain aspects, the tubular portion may comprise a rolled or wrappedconfiguration.

In certain aspects, the tubular portion may have a structure comprisingno gaps or seams therein.

In certain embodiments of the present disclosure, a method offabricating a sensor configured for at least partial implantation withina subject may comprise providing a planar substrate material having anon-implantable proximal portion and an implantable distal portion, andforming the distal portion of the substrate material into a tubularstructure.

In certain aspects, the forming of the tubular distal portion maycomprise wrapping the planar distal portion.

In certain aspects, wrapping the planar distal portion may comprisewrapping the planar distal portion around a cylindrical shaped mandrel.

Certain aspects may include applying heat to the cylindrically wrappeddistal portion.

In certain aspects, wrapping the planar distal portion may compriseplacing opposing side edges of the planar distal portion in an apposedconfiguration.

In certain aspects, the apposed configuration may comprise placing theside edges in an edge-to-edge configuration.

In certain aspects, the apposed configuration may comprise placing theside edges in an overlapping configuration.

In certain aspects, wrapping the planar distal portion may comprisehelically winding the planar distal portion.

In certain aspects, the forming of the tubular distal portion maycomprise an extrusion process.

The preceding merely illustrates the principles of the presentdisclosure. It will be appreciated that those skilled in the art will beable to devise various arrangements which, although not explicitlydescribed or shown herein, embody the principles of the presentdisclosure and are included within its spirit and scope. Furthermore,all examples and conditional language recited herein are principallyintended to aid the reader in understanding the principles of thepresent disclosure and the concepts contributed by the inventors tofurthering the art, and are to be construed as being without limitationto such specifically recited examples and conditions. Moreover, allstatements herein reciting principles, aspects, and embodiments of thepresent disclosure as well as specific examples thereof, are intended toencompass both structural and functional equivalents thereof.Additionally, it is intended that such equivalents include bothcurrently known equivalents and equivalents developed in the future,i.e., any elements developed that perform the same function, regardlessof structure. The scope of the present disclosure, therefore, is notintended to be limited to the exemplary embodiments shown and describedherein. Rather, the scope and spirit of present disclosure is embodiedby the appended claims.

1-28. (canceled)
 29. A medical device comprising: an elongate bodyhaving an arcuate exterior surface; and a sensor body comprising adistal portion with a flat exterior surface fixedly coupled to thearcuate exterior surface of the elongate body, wherein the distalportion comprises an electrode adapted to sense an analyte level in ahuman body.
 30. The medical device of claim 29, wherein the sensor bodycomprises: a front side where the electrode is present; and a back sidewhere the flat exterior surface is present.
 31. The medical device ofclaim 30, wherein both the front side and back side of the distalportion are flat such that the distal portion has a flat design.
 32. Themedical device of claim 31, wherein the elongate body is an elongatetubular body.
 33. The medical device of claim 32, further comprising anelongate sharp body adapted for insertion into the elongate tubularbody.
 34. The medical device of claim 31, wherein the elongate body isnon-tubular.
 35. The medical device of claim 30, wherein the distalportion comprises a plurality of electrodes.
 36. The medical device ofclaim 29, further comprising an adhesive fixedly coupling the flatexterior surface of the distal portion to the arcuate exterior surfaceof the elongate body.
 37. The medical device of claim 29, wherein themedical device is adapted such that it is implantable to a desired depthbeneath a skin surface.
 38. The medical device of claim 37, wherein themedical device is adapted such that that it is at least partiallyimplantable beneath an epidermal layer of the skin.
 39. The medicaldevice of claim 29, wherein the elongate body has a width and the sensorbody has a width, and wherein the width of the elongate body issubstantially the same as the width of the sensor body.
 40. The medicaldevice of claim 29, wherein the elongate body has a width and the sensorbody has a width, and wherein the width of the elongate body is largerthan the width of the sensor body.
 41. The medical device of claim 29,wherein the analyte level is a glucose level.